Conventionally, in radio communication terminals such as a cellular telephone device, communication is performed by selecting one of a plurality of communication systems (for example, communication systems with different frequency bands or different base stations) and establishing synchronization therewith. Here, since the plurality of communication systems are prioritized, the radio communication terminal takes measures for communicating with a communication system with a higher priority.
For example, in a case in which a radio communication terminal performing re-selection has established synchronization with a non-prior system and is in a standby state, the radio communication terminal tries acquisition of a communication system with a higher priority than that of this non-prior system for a certain time period. On this occasion, if reception quality of a prior system signal coming from another base station is satisfactory, synchronization is established with this prior system, and the state transitions to a standby state.
Moreover, in recent years, many types of radio communication terminals with a sub antenna in addition to a main antenna have been introduced. More and more of these radio communication terminals are made so as to employ a method for receiving a channel (e.g., a standby paging channel for audio communication) by the sub antenna instead of the main antenna, by using an SHDR (Simultaneous Hybrid Dual Receive) function.
For example, Patent Document 1 discloses a module for performing communication in which two antennas acquire different channels at the same time, and a channel with higher reception sensitivity among the two received channels is used.
Patent Document 1: Japanese Unexamined Patent Application, First Publication No. 2005-184355